1. Field of the Invention
This application is directed to quaternary ammonium salt reaction products derived from heterocyclics such as thiadiazoles as multifunctional antioxidant/antiwear additives for lubricants and fuels and to compositions containing same.
2. Description of Related Art
The use of thiadiazole derivatives, such as 2,5-dimercapto-1,2,4-thiadiazole, for their antioxidant, anticorrosion and metal passivating properties when incorporated into oleaginous compositions is well known as disclosed in U.S. Pat. Nos. 4,661,273, 4,678,592 and 4,584,114. U.S. Pat. No. 4,410,703 discloses the use of thiadiazoles substituted with other moieties such as the organophosphorous moiety.
The use of alkenyl succinic acid-esters has been reported as rust inhibitors and dispersants for a variety of lubricating oils and greases.
However, organic ammonium salt antioxidants have received little or no attention in the past as lubricant additives. While developing new antioxidants for mineral oil base stock and synthetic stock based lubricants, we discovered that organic ammonium salts could display remarkable antioxidant and antiwear properties when derivatized with certain synergistic hetercyclic species. The key design of this class of unique antioxidant appears to be the combination of an antioxidant moiety and an organic cation. Various types of antioxidant and organic cations can be used effectively. The resulting products are generally soluble in synthetic lubricants; including synthetic hydrocarbon esters and the like. Many are also soluble in less polar mineral base stocks containing high percentages of paraffinic or paraffinic-like components. Solubility in mixed base stocks formulated with mixtures of synthetic and mineral oil blending components is good.